| This study investigated effects of two drugs of abuse, viz. cocaine (a stimulant of the central nervous system) and morphine (a depressant of the central nervous system), on two selected parameters of visual function: (1) the quality of nerve impulses produced by retinal photoreceptors and bipolar cells upon the action of light, as measured by the a- and b-wave amplitudes of electroretinogram (ERG), and (2) the wavelength of maximum absorbance ((lamda)(,max)) of the major photosensitive pigment, rhodopsin.;Results showed reduction of a- and b-wave amplitudes under the influence of cocaine, and increase of a- and b-wave amplitudes under the influence of morphine. ERG pattern was distorted by both drugs. High correlation was found between changes of a- and b-wave amplitudes and drug dose levels. (lamda)(,max) of rhodopsin remained unchanged under the influence of the two drugs.;The experimental design used involved dark adapting rabbits and recording their ERGs using standard technique, while the animals are used as controls (saline injection) or under the influence of varying doses of drugs. Timed test-flash was used as the light stimulus. The form and the amplitude of a- and b-waves was studied. Pharmacokinetic study on cocaine and morphine using corresponding drug doses was performed. Actual concentrations of drugs in blood were determined by u.v. absorption method. The (lamda)(,max) of rhodopsin under control and drug condition was determined by excising the eyes, removing the retinas and solubilizing the visual pigment. |
